Hydraulic syringe and method of manufacture

ABSTRACT

A manually operated hydraulic syringe includes a syringe barrel. The syringe barrel has an interior surface bounding a chamber extending from a first end to an opposing second end. A manual plunger has a distal end slidably disposed within the first end of the chamber. A hydraulic plunger is slidably enclosed within the second end of the chamber. Sealed in substantial isolation within the syringe barrel is a hydraulic fluid, such as water or oil. Coupled to the distal end of the syringe barrel is a nozzle or cartridge in which a dispensing material, such as a high viscosity fluid, can be selectively disposed. Manual advancement of the manual plunger within the first chamber results in pressurization of the hydraulic fluid. In turn, the pressurized hydraulic fluid advances the hydraulic plunger under a force greater than the force applied to the manual plunger. Advancement of the hydraulic plunger within the syringe body functions to dispense the dispensing material from the attached nozzle or cartridge.

This application is a continuation in part of U.S. patent applicationSer. No. 09/467,419, filed Dec. 20, 1999, which for purposes ofdisclosure is incorporated herein by specific reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to syringes. Specifically, the presentinvention relates to manually operated hydraulic syringes and methods ofmanufacture.

2. Prior State of the Art

Syringes are widely used to inject, dispense and extract fluids in acontrolled fashion. Conventional syringes generally consist of a syringebody having a cylindrical chamber in which a piston is forced to slide.The chamber has an orifice in the end opposite the piston such that ifthe piston is pushed towards the orifice, fluid is ejected from thechamber into or onto a target. If the piston is forced away from theorifice, fluid at the orifice is vacuumed into the chamber.

As apparent, a source of force is needed to operate a syringe. Anon-human driving mechanism, such as an electrical motor, provides thisforce in automated syringes. Many syringes, however, operate under themanual force of a user. Although typically less sophisticated thanautomated syringes, manual syringes are widely used because they areinexpensive, easily maneuverable, disposable, and do not require complexand bulky driving mechanisms.

Syringes are often used in dispensing high viscosity fluids. Forexample, in dentistry, high viscosity fluids such as uncured dentalfilling materials are often dispensed onto small targets such as apre-drilled tooth cavity. Dispensing high viscosity fluids, however,requires the user to exert a relatively high force on the manualsyringe. This required exertion can produce undesired stress and fatigueon the user. Furthermore, dispensing high viscosity fluids can be moredifficult to control. For example, because of the high exertion forcerequired to dispense high viscosity materials, it can be difficult todispense small controlled amounts or to dispense the material at aconstant or desired flow rate. The high exertion force can also resultin the operator's hand becoming shaky or unstable. Such shaking and lackof control can result in the fluid missing the target.

In one approach to overcome some of the above problems, devices such ascaulking type guns have been used to dispense high viscosity fluids.Caulking type guns have a levered handle which produces a mechanicaladvantage. Such devices, however, are large and cumbersome relative toconventional syringes. Furthermore, some caulking type guns operate on aratcheting system which makes it difficult to dispense in a smooth,continuous manner. Finally, since caulking type guns have a handle thatorthogonally projects from the barrel, caulking type guns are limited intheir use and maneuverability

Therefore, an easily maneuverable apparatus and method are desired forthe controlled manual dispensing of high viscosity fluids.

BRIEF SUMMARY OF THE INVENTION

A hydraulic syringe includes a syringe barrel having an exterior surfaceand an interior surface. A syringe grip outwardly projects from theexterior surface of the syringe barrel. The interior surface of thesyringe barrel bounds a chamber having a substantially uniformtransverse cross sectional area along its length. Sealed within thechamber is a hydraulic fluid. A manual plunger is coupled with the firstend of the barrel so as to selectively advance within the chamberthereof. A hydraulic plunger is slidably disposed within the second endof the barrel. As the manual plunger is advanced, the hydraulic fluid ispressurized which in turn causes the hydraulic plunger to advance.

One of the unique features of the present invention is that the manualplunger has a transverse cross sectional area that is smaller than themaximum transverse cross sectional area of the hydraulic plunger. As aresult, a hydraulic advantage is achieved. That is, as the manualplunger is advanced within the chamber under a first force at a firstspeed, the hydraulic fluid is pressurized. In turn, the pressurizedhydraulic fluid pushes against the hydraulic plunger. As a result of thehydraulic plunger having a larger surface area of displacement, thehydraulic plunger moves forward with a second force that is greater thanthe first force and at a second speed that is slower than the firstspeed. In turn, this magnified or increased second force is appliedthrough the hydraulic plunger to the high viscosity fluid fordispensing.

Once the material has been dispensed by the hydraulic syringe, a springdisposed between the hydraulic plunger and the second end of the barrelis used to help retract the hydraulic plunger. Furthermore, one or moreretraction rods are secured to the hydraulic plunger so as to projecttowards the first end of the syringe barrel. A guide is mounted on andradially outwardly projects from the manual plunger. Each rod extendsthrough a passageway formed on the guide such that the guide can freelyslide along the length of each rod. However, the rods are also formedsuch that as the manual plunger is retracted, the guide secures to theend of each rod resulting in both the rods and the hydraulic plungerbeing retracted as the manual plunger is retracted.

In the above embodiment, as a result of the magnification of force,minimal manual force is required to be applied by the user of thehydraulic syringe to effectively dispense high viscosity fluids in acontrolled manner. Furthermore, since minimal force and thus minimalexertion is required by the user, fatigue and shaking by the user isalso minimized. Finally, since the hydraulic syringe has a configurationsimilar to a conventional syringe, the hydraulic syringe is convenientand easily maneuvered by the user. That is, rotation of the wristfacilitates quick and easy placement for most delivery angles.

These and other features and advantages of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained, a more particular descriptionof the invention briefly described above will be rendered by referenceto specific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 is an isometric view of one embodiment of a hydraulic syringe;

FIG. 2 is an exploded isometric view of the syringe of FIG. 1;

FIG. 3 is an isometric view of the syringe of FIG. 1 with the syringebarrel viewed in cross section and with the grip removed to show thehydraulic advantage of the syringe;

FIG. 4 is an isometric view of the syringe of FIG. 3 wherein theplungers are advanced under a force;

FIG. 5 is a partial cross section isometric view of an alternativeembodiment of a hydraulic syringe, wherein the barrel has a singlechamber;

FIG. 6 is a partial cross section isometric view of an alternativeembodiment of a hydraulic syringe having an inner barrel and outerbarrel;

FIG. 7 is a partial cross sectional side view of the hydraulic syringeshown in FIG. 6;

FIG. 8 is a cross sectional side view of an alternative embodiment of ahydraulic syringe wherein the manual plunger has a channellongitudinally extending there through;

FIG. 9 is a cross sectional side view of an alternative embodiment of ahydraulic syringe having a slidable rod disposed within the manualplunger;

FIG. 10 is a cross sectional side view of another alternative embodimentof a hydraulic syringe;

FIG. 11 is a cross sectional side view of the guide shown in FIG. 10taken along section lines 11—11;

FIG. 12 is a cross sectional side view of the sealing assembly shown inFIG. 10;

FIG. 13 is a cross sectional side view of the hydraulic plunger shown inFIG. 10;

FIG. 14 is cross sectional side view of the cartridge shown in FIG. 10separated from the syringe barrel;

FIG. 15 is a cross sectional side view of the mounting arm projectingfrom the end of the syringe shown in FIG. 10;

FIG. 16 is a perspective disassembled view of yet another alternativeembodiment of a hydraulic syringe;

FIG. 17 is a cross sectional side view of the syringe shown in FIG. 16partially assembled to a first stage;

FIG. 18 is a cross sectional side view of the syringe shown in FIG. 16partially assembled to a second stage; and

FIG. 19 is a cross sectional side view of the fully assembled syringeshown in FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a syringe 100 is manually operated by squeezing ahandle 110 towards a grip 150. This manual force is hydraulicallyconverted within syringe 100 into an increased force which urges workingmaterial from a nozzle 230 out through an orifice 231 thereof. In thedescription and claims, “hydraulically” is defined as “of, involving,moved, or operated by pressurized fluid including any fluid in theliquid or gaseous phases.” As a result of producing an increased forcefrom an initial manual force, the inventive syringe can be used to moreeasily dispense highly viscous materials.

The term “syringe” as used in the specification and appended claims isbroadly intended to include all types of dispensing apparatus whichinclude a hollow barrel and a plunger. The inventive syringes can beused for medical uses and non-medial uses, such as industrial and homeuse. Furthermore, although the inventive syringes are depicted herein ashaving a configuration similar to a conventional medical syringe, theinventive syringe may also have the configuration of a caulking gun orother apparatus used in dispensing material.

The structural and operational details of syringe 100 are now describedwith reference to FIG. 2 which shows syringe 100 in an exploded view,and FIG. 3 which shows a portion of syringe 100 in cross-section. Thestructure of syringe 100 will be described in order beginning withhandle 110 at the upper right corner of FIGS. 2 and 3 and proceedingdiagonally downwards and to the left, finishing with nozzle 230 at thelower left corner of FIGS. 2 and 3.

As depicted in FIG. 2, handle 110 includes an enlarged annular rest 112having a front face 113. Projecting from front face 113 is a tubularstem 114. Stem 114 bounds a cylindrical hole 111.

An elongated manual plunger 120 has a proximate end 121 and an opposingdistal end 122. In this description and in the claims, “distal” meanstowards the lower left corner of FIGS. 1-3 and “proximate” means towardsthe upper right corner of FIGS. 1-3. Proximate end 121 of manual plunger120 is attached to handle 110 by being inserted within cylindrical hole111. In an alternative embodiment, handle 110 can be integrally moldedwith manual plunger 120. In yet other embodiments, handle 110 and manualplunger 120 can be mechanically, chemically, or otherwise securedtogether. Encircling distal end 122 of manual plunger 120 is an annulargroove 123. Groove 123 is configured to receive a flexible seal 130.Seal 130 and other seals set forth in the specification and appendedclaims are broadly intended to include o-rings, loaded lip seals,including those with bevel lips, packing material, gaskets, and anyother conventional type of seal or sealing material. Examples of loadedlip seals include Standard PolyPak, Deep PolyPak, and Pip Sealsavailable from Parker Seals out of Irving, Calif.

Proceeding diagonally downwards and to the left, a tubular grip retainer140 bounds a passageway 144 extending there through. Grip retainer 140includes a first collar portion 141 having a first outer diameter and asecond collar portion 142 concentrically aligned with first collarportion 141. Second collar portion 142 has a second outer diameterlarger than the first outer diameter. A slot 143 longitudinally extendsalong the length of grip retainer 140. Slot 143 enables grip retainer140 to selectively radially expand and constrict. An elongated grip 150has a front face 154, an opposing back face 155, and an aperture 156centrally extending therebetween. Grip retainer 140 is used to securegrip 150 to a syringe barrel 160. Specifically, syringe barrel 160 hasan elongated tubular configuration with an exterior surface 151 thatlongitudinally extends between a proximate end 152 and an opposingdistal end 153. As depicted in FIG. 3, an annular lip 158 radiallyoutwardly projects from exterior surface 151 at proximate end 152.

During assembly, as depicted in FIG. 2, proximate end 152 of syringebarrel 160 is received through aperture 156 of grip 150 so that grip 150is distal of lip 158. Next, proximate end 152 of syringe barrel 160 isreceived through passageway 144 of grip retainer 140 so that secondcollar portion 142 of grip retainer 140 is distal of lip 158. Grip 150is then slid proximal such that first collar portion 141 of gripretainer 140 is received within the remainder of aperture 156 extendingbetween syringe barrel 160 and grip 150. Aperture 156 is configured suchthat as first collar portion 141 is received within aperture 156, gripretainer 140 is constricted by the closure of slot 143. The closure ofslot 143 results in grip retainer 140 biasing in frictional engagementagainst exterior surface 151 of syringe barrel 160. In this constrictedposition, grip retainer 140 is also biased against lip 158 which acts asa stop to prevent grip retainer 140 from sliding proximal. In turn, grip150 is biased against second collar portion 142 which acts as a stop topreclude grip 150 from further sliding proximal. In alternativeembodiments, grip 150 can be secured by alternative means such asadhesion or mechanical locking. In yet other embodiments, grip 150 canbe integrally molded with syringe barrel 160.

Returning to FIG. 3, syringe barrel 160 includes a first tubular portion161 and an adjacent second tubular portion 162. First tubular portion161 has an interior surface 163 that bounds a first chamber 164 andlongitudinally extends from proximal end 152 to a distal end 166. In theembodiment depicted, first chamber 164 has a substantially cylindricaltransverse cross sectional area with a diameter D₁. In this descriptionand in the claims, “transverse” means in a plane perpendicular to thelongitudinal axis (X) of syringe 100.

Distal end 122 of manual plunger 120 is configured to be received withinfirst chamber 164 such that distal end 122 is slidable therein along therange (Q). Furthermore, manual plunger 120 is configured such that seal130 biases against interior surface 163 bounding first chamber 164 so asto effect a liquid tight seal as manual plunger 120 is advanced andretracted within first chamber 164. In yet other embodiments, seal 130can be replaced with a rubber bulb or other means for effecting a liquidtight seal between manual plunger 120 and interior surface 163 as manualplunger 120 is advanced and retracted within first chamber 164.

Second tubular portion 162 of syringe barrel 160 includes an interiorsurface 167 bounding a second chamber 165. Second chamber 165longitudinally extends from a proximal end 168 to distal end 153. In theembodiment depicted, second chamber 165 has a substantially cylindricaltransverse cross sectional area with a diameter D₂. Diameter D₂ islarger than diameter D₁. As such, the transverse cross sectional area ofsecond chamber 165 is larger than the transverse cross sectional area offirst chamber 164. Second tubular portion 162 is concentrically coupledwith first tubular portion 161 such that first chamber 164 is fluidcoupled with second chamber 165.

Slidably disposed within second chamber 165 is a hydraulic plunger 180.In the embodiment depicted, hydraulic plunger 180 includes a cylindricalhead 181 having a perimeter groove 183 configured to receive an annularseal 170. Projecting from a front face 184 of head 181 is a shaft 182.Hydraulic plunger 180 is configured such that when received withinsecond chamber 165, seal 170 biases against interior surface 167 so asto effect a liquid tight seal as hydraulic plunger 180 advances andretracts within second chamber 165 along range (q).

Prior to use, as depicted in FIG. 3, a hydraulic fluid (S), such aswater, a saline solution, oil, or a gas, is sealed within syringe barrel160 between distal end 122 of manual plunger 120 and head 181 ofhydraulic plunger 180. One example of a hydraulic fluid is polydimethyalsiloxane having a viscosity in a range between about 10 centistoke toabout 100,000 centistoke, with about 500 centistoke to about 5,000centistoke being more preferred.

In one method for incorporating hydraulic fluid (S), distal end 122 ofmanual plunger 120 is slidably moved to the most distal end of range(Q). Hydraulic fluid (S) is then poured into second chamber 165 throughopen distal end 153 of syringe barrel 160 so as to substantially fillsecond chamber 165. Next, hydraulic plunger 180 is inserted withindistal end 153 of syringe barrel 160 so as to effectively seal offhydraulic fluid (S) from the ambient environment. Accordingly, as manualplunger 120 is withdrawn within first chamber 164, hydraulic fluid (S)flows into first chamber 164 while hydraulic plunger 180 advances withinsecond chamber 165 under the vacuum force produced by manual plunger120.

As depicted in FIG. 4, during use an operator manually applies a force(F₁) to handle 110 so that distal end 122 of the manual plunger 120slides towards the distal end of first chamber 164. The applied force(F₁) produces a positive pressure (P) on the hydraulic fluid (S) withrespect to the ambient pressure. The pressure (P) produced on hydraulicfluid (S) within first chamber 164 is calculated based on Equation (1):

P=F ₁ /A ₁   (1)

where A₁ is the transverse cross sectional area of manual plunger 120which is exposed to the hydraulic fluid. In the present embodiment, area(A₁) is thus also equal to the transverse cross sectional area of firstchamber 164.

This resulting pressure (P) of the hydraulic fluid is exerted againsthead 181 of hydraulic plunger 180 which causes hydraulic plunger 180 toslide distally within second chamber 165. Head 181 has a transversecross sectional area (A₂) which is exposed to the hydraulic fluid. Inthe present embodiment, area (A₂) is equal to the transverse crosssectional area of second chamber 165. As hydraulic plunger 180 slidesdistally, hydraulic fluid (S) fills within second chamber 165. As aresult of area (A₂) being larger than area (A₁), a resulting increasedforce (F₂) is applied on hydraulic plunger 180 through a hydraulicadvantage. This force (F₂) is not only the force that is applied tohydraulic plunger 180 but is also the force, as discussed below, thathydraulic plunger 180 uses to dispense viscous fluids from syringe 100.The hydraulic force (F₂) is calculated based on the following Equation(2):

F ₂ =F ₁ ×A ₂ /A ₁   (2)

Thus, if the transverse cross sectional area (A₂) of hydraulic plunger180 is twice as big as the transverse cross sectional area (A₁) ofmanual plunger 120, force F₂ is twice as big as the force F₁ applied tohandle 110. As a result of this hydraulic advantage producing a largerforce on hydraulic plunger 180, it is easier for a user of syringe 100to dispense highly viscous fluids at a constant and steady rate usingminimal force and exertion.

In one embodiment, the diameter D₁ of first chamber 164 is in a rangebetween about 0.8 inches (2 cm) to about 0.02 inches (0.05 cm), withabout 0.4 inches (1 cm) to about 0.1 inches (0.25 cm) being morepreferred. The diameter D₂ of second chamber 165 is typically in a rangebetween about 2 inches (5 cm) to about 0.07 inches (0.2 cm), with about0.8 inches (2 cm) to about 0.2 inches (0.5 cm) being more preferred. Theratio of A₂/A₁ is typically in a range between about 1 to about 7, withabout 3 to about 5 being more preferred. The above dimension, of course,are only by way of example and can change dramatically depending on theintended use.

The present invention envisions that there are a variety of alternativeembodiments that can be used to achieve the hydraulic advantage. Forexample, although the transverse cross-sectional shape of the first andsecond chambers is shown as being circular, chambers of anyconfiguration in which a plunger can slide are equivalent. It isevident, of course, that the corresponding plungers will need to havecomplementary shapes. Other embodiments for achieving a hydraulicadvantage are disclosed below.

It is also noted that the difference in the transverse cross sectionalarea between the first chamber and the second chamber can be very slightor large and in both embodiments a hydraulic advantage is obtained. Thesmaller the variance, the smaller the hydraulic advantage. The actualsize of the syringe and the variance between the transverse crosssectional areas of the plungers is dependent in part on the type,viscosity, and amount of fluid to be dispensed.

The depicted embodiment discloses the manual and hydraulic plungerssliding along a common longitudinal axis (X). The present invention alsoenvisions that the plungers can slide along non-common axises.Furthermore, the sliding direction of the hydraulic plunger may be otherthan the direction of the manual plunger.

The present invention also envisions that there are a variety ofalternative embodiments for coupling the viscous material with syringe100 for dispensing by hydraulic plunger 180. For example, depicted inFIGS. 2 and 3, an end cap 200 includes a base plate 203 having anaperture 201 extending there through. Aperture 201 is configured toreceive shaft 182 of hydraulic plunger 180. Projecting from the frontface of base plate 203 is an annular collar 204 having a pair of bayonetslots 202 formed therein. End cap 200 is fitted within an annulargrooved slot 206 formed within second chamber 165. A flexible C-shapedlocking clip 210 is also disposed within grooved slot 206 to preventinadvertent removal of end cap 200 from syringe barrel 160. An annularseal 190 is biased between end cap 200 and syringe barrel 160 to effecta secure, snug fitting. In this configuration, shaft 182 of hydraulicplunger 180 is disposed within and/or aligned with aperture 201 of endcap 200.

Nozzle 230, which in one embodiment comprises a disposable cartridge,includes a sidewall 223 extending from a proximate end 224 to andopposing distal end 225. Sidewall 223 bounds an interior compartment inwhich the material for dispensing is disposed. Outwardly projecting fromproximal end 224 are a pair of bayonet connectors configured forselective locking with bayonet slots 202. Formed at distal end 225 is anoutlet orifice through which the material is expelled. In the embodimentdepicted, a nozzle plunger 220 is slidably disposed within proximal end224 of nozzle 230.

Prior to attachment of nozzle 230, manual plunger 120 is pulled backinto its most proximate position such that hydraulic plunger 180 is alsopulled back into its proximate position. In this position, nozzle 230 ismechanically locked into end cap 200 by inserting bayonet connectors 232into bayonet slots 202 of end cap 200 and slightly twisting nozzle 230about the longitudinal axis (X).

To facilitate dispensing, manual plunger 120 is advanced which in turnadvances hydraulic plunger 180 under a hydraulic force as previouslydiscussed. As hydraulic plunger 180 advances, shaft 182 pushes againstnozzle plunger 220 which in turn advances nozzle plunger 220 withinnozzle 230. As nozzle plunger 220 advances, the dispensing materialdisposed therein is ejected out through orifice 231. In alternativeembodiments, nozzle plunger 220 can be removed and shaft 182 canfunction as the plunger for directly dispensing the material from nozzle230.

In yet another embodiment, it is also envisioned that a nozzle tip canbe threadedly or otherwise removably mounted directly to distal end 153of syringe barrel 160. The dispensing material can then be selectivelypositioned within second chamber 165 when hydraulic plunger 180 is inthe proximate position. By advancing plungers 120 and 180, cylindricalhead 181 of hydraulic plunger 180 functions to press the material out ofthe nozzle tip. In this embodiment, it is envisioned that shaft 182 canbe removed from head 181. In alternative embodiments, shaft 182 can havethe same diameter as head 181.

The present invention includes means for hydraulically producing anincreased force against dispensing material within nozzle 230 when aninitial force is applied to manual plunger 120, the increased forcebeing greater than the initial force. One example of such means includeshydraulic plunger 180 having the transverse cross sectional area A₂greater than the transverse cross sectional area A₁ of manual plunger120, as previously discussed with regard to FIGS. 3 and 4.

The present invention, however, envisions that there are a variety ofalternative plunger and barrel configuration that also function tohydraulically produce an increased force against the dispensingmaterial. For example, depicted in FIG. 5 is an alternative embodimentof an inventive syringe 240 that is also configured to produce ahydraulic advantage for dispensing highly viscous material. Syringe 240includes a barrel 242 longitudinally extending from a first end 244 toan opposing second end 246. Barrel 242 has an interior surface 248 thatbounds a chamber 250. In the embodiment depicted, chamber 250 has asubstantially cylindrical configuration having a diameter D₃ and acorresponding transverse cross sectional area.

Outwardly projecting from the side of barrel 242 are finger grips 241.Barrel 242 terminates at second end 246 at an end wall 245. Outwardlyprojecting from end wall 245 is a female coupler 268. Coupler 268includes a tubular spout 270 encircled by a threaded sleeve 272. In oneembodiment, coupler 268 comprises a portion of a Luer Lock connector.Spout 270 bounds a passageway 271 that facilitates communication betweenchamber 250 and the exterior. A vent port 273 extends through end wall245 and exits between spout 270 and threaded sleeve 272. In alternativeembodiments, vent port 273 can exit outside of sleeve 272.

Threadedly mounted at first end 244 of barrel 242 is a tubular bushing252. Bushing 252 has an exterior surface 254 that is sealed againstinterior surface 248 of barrel 242. Bushing 252 also has an interiorsurface 256 that bounds an opening 258 extending there through. A seal259 is mounted on interior surface 256 so as to encircle opening 258.

Slidably disposed within opening 258 of bushing 252 is a manual plunger260 having an elongated, substantially cylindrical shaft-likeconfiguration. Manual plunger 260 has a first end 262, an opposingsecond end 264, and a diameter D₄ with a corresponding transverse crosssectional area. Diameter D₄ and corresponding transverse cross sectionalarea of manual plunger 260 are smaller than diameter D₃ andcorresponding transverse cross sectional area of chamber 250.

Mounted at first end 262 of manual plunger 260 is an enlarged handle266. Second end 264 of manual plunger 260 is disposed within chamber 250of barrel 242. Radially outwardly projecting from second end 264 ofmanual plunger 260 is a guide 267. Guide 267 facilitates alignment ofmanual plunger within chamber 250 and prevents accidental removal ofmanual plunger 260 through bushing 252. Manual plunger 260 is biased insealed engagement against o-ring 259. As such, a liquid tight seal ismaintained between manual plunger 260 and bushing 252 as manual plunger260 is selectively advanced and retracted through bushing 252.

Slidably disposed within second end 246 of chamber 250 is hydraulicplunger 180. Hydraulic plunger 180 and its corresponding elements werepreviously discussed with regard to FIGS. 2 and 3. As depicted in FIG.5, o-ring 170 mounted on head 181 of hydraulic plunger 180 is slidablybiased in sealed engagement against interior surface 248 of chamber 250.As such, hydraulic plunger 180 has a maximum diameter and correspondingtransverse cross sectional area substantially equal to diameter D₃ andthe corresponding transverse cross sectional area of chamber 250.Mounted at the end of shaft 182 projecting from head 181 is a sealingbulb 274.

Removably coupled with second end 246 of barrel 242 is a nozzle 276.Nozzle 276 has a first end 278 with threads 280 outwardly projectingtherefrom. Nozzle 276 also has an opposing second end 282 with aconstricted exit orifice 284 formed thereat. Nozzle 276 bounds acompartment 286 configured to hold a dispensing material. Nozzle 276 isconfigured such that first end 278 of nozzle 276 can be threadedlyengaged with threaded sleeve 272. In this configuration, spout 270 andsealing bulb 274 are received within compartment 286 of nozzle 276.Sealing bulb 274 is configured to bias in sealed engagement against theinterior surface bounding compartment 286 as bulb 274 is advanced andretracted within compartment 286.

During operation, a hydraulic fluid is sealed between bushing 252 andhead 181 of hydraulic plunger 180. As manual plunger 260 is advancedwithin chamber 250 of barrel 242, the pressure on the hydraulic fluid isincreased. In turn, the hydraulic fluid presses against hydraulicplunger 180, thereby slidably advancing hydraulic plunger 180 towardsend wall 245 of barrel 242. As hydraulic plunger 180 advances, the airbetween head 181 and end wall 245 escapes through vent port 273.Furthermore, as hydraulic plunger 180 advances, bulb 274 advances withinchamber 286 of nozzle 276, thereby pressing the material containedtherein out through exit orifice 284.

Because manual plunger 260 has a substantially uniform transverse crosssectional area that is smaller than the transverse cross sectional areaof head 181, advancing manual plunger 260 under a first force at a firstspeed result in a hydraulic change or advantage which moves hydraulicplunger 180 under a second force, which is greater than the first force,and at a second speed, which is slower than the first speed. As aresult, syringe 240 is effective for dispensing highly viscous materialin a controlled manner using minimal exertion.

Depicted in FIG. 6 is yet another embodiment of an inventive syringe 290which produces a desired hydraulic advantage. Syringe 290 includes abarrel 292. Barrel 292 includes an outer barrel 294 and an inner barrel296. Outer barrel 294 has an interior surface 298 that bounds a chamber304 and extends between an first end 300 and an opposing second end 302.Outwardly projecting from first end 300 of outer barrel 294 is anannular flange 306. Flange 306 has an annular front face 305 thatterminates at an annular ridge 307. Front face 305 is substantially flatand is disposed in a plane perpendicular to the longitudinal axis ofsyringe 290. Flange 306 also includes an annular back face 309 thatinwardly slopes from ridge 307 to the outer surface of outer barrel of294.

Outer barrel 294 terminates at second end 302 at an end wall 315.Extending through end wall 315 is a vent port 317. Projecting from endwall 315 is female coupler 268, as previously discussed with regard toFIG. 5. Finger grips 308 outwardly project from outer barrel 294 betweenfirst end 300 and opposing second end 302.

Inner barrel 296 includes an elongated tubular sleeve 310 having aninterior surface 312 and an exterior surface 314 each extending betweena first end 316 and an opposing second end 318. Exterior surface 314 oftubular sleeve 310 has a configuration substantially complementary tointerior surface 298 of outer barrel 294. As such, tubular sleeve 310 isselectively slid within outer barrel 294. Encircling tubular sleeve 310is an annular seal 311. Seal 311 produces a liquid tight seal betweenexterior surface 314 of tubular sleeve 310 and interior surface 298 ofouter barrel 294.

Inner barrel 296 also includes a substantially U-shaped clamp 320encircling and outwardly projecting from first end 316 of tubular sleeve310. As depicted in FIG. 7, clamp 320 includes an annular first arm 322radially outwardly projecting from first end 316 of tubular sleeve 310;an annular second arm 324 projecting from the distal end of first arm322 in substantially parallel alignment with the longitudinal axis ofsyringe 290; and an annular third arm 326 inwardly projecting from thedistal end of second arm 324. Third arm 326 terminates an annular ridge328 and includes an annular engagement face 330 that outwardly slopesfrom annular ridge 328.

During assembly, second end 318 of inner barrel 296 is slidably receivedwithin outer barrel 294. Inner barrel 296 is advanced until engagementface 330 of clamp 320 contacts annular ridge 307 of flange 306. As aresult of engagement face 330 being sloped, additional force on innerbarrel 296 results in radial outward expansion of third arm 326 untilannular ridge 328 of clamp 320 passes over annular ridge 307 of flange306. Third arm 326 then resiliently inwardly constricts to bias againstback face 309 of flange 306, thereby mechanically securing outer barrel294 and inner barrel 296 together. As a result of back face 309 beinginwardly sloped, third arm 326 is urged forward to maintain a secureengagement. In one embodiment, the engagement between outer barrel 294and inner barrel 296 is sufficient to produce a liquid tight sealtherebetween. In alternative embodiments, seal 311 can be used.

As depicted in FIGS. 6 and 7, interior surface 312 of inner barrel 296bounds a first chamber 332 longitudinally extending through inner barrel296. First chamber 332 has a substantially cylindrical configurationwith an inner diameter D₅. An annular groove 334 is formed on interiorsurface 312 of inner barrel 296 at first end 316. Disposed adjacent toannular groove 334 is an inwardly projecting annular shoulder 346.Disposed within groove 334 is an annular seal 336.

Slidably disposed within first chamber 332 is a manual plunger 338.Manual plunger 338 has a first end 340 with a handle 342 disposedthereat and an opposing second end 344 disposed within first chamber332. Manual plunger 338 has a substantially cylindrical shaft-likeconfiguration having a diameter D₆. Manual plunger 338 is slidablybiased against seal 336 so as to affect a liquid tight seal betweenmanual plunger 338 and inner barrel 296 at seal 336. Disposed at secondend 344 of manual plunger 338 is a guide 348. Guide 348 has a diameterslightly larger than the diameter of manual plunger 338 and isconfigured to hit against shoulder 346 so as to prevent manual plunger338 from accidentally being pulled out of barrel 290. Guide 348 alsofacilitates alignment of manual plunger within barrel 292. Inalternative embodiments, guide 348 may or may not effect a liquid tightseal against interior surface 312 of inner barrel 296.

As depicted in FIGS. 6 and 7, inner barrel 296 has a shorter length thanouter barrel 294. As a result, a substantially cylindrical secondchamber 350 is formed between inner barrel 296 and an end wall 315 ofouter barrel 294. Second chamber 350 has a diameter D₇ that is largerthan diameter D₆ of manual plunger 338. Slidably disposed within secondchamber 350 is hydraulic plunger 180 as previously discussed with regardto FIG. 5. Seal 170 mounted on head 181 of hydraulic plunger 180 isslidably biased in sealed engagement against interior surface 298 ofouter barrel 294 bounding second chamber 350. As such, hydraulic plunger180 as used in FIGS. 6 and 7 has a maximum diameter substantially equalto diameter D₇ of second chamber 350.

Nozzle 276 as previously discussed with regard to FIG. 5 is secured tosecond end 302 of outer barrel 294. Shaft 182 and bulb 274 are disposedwithin compartment 286 such that as hydraulic plunger 180 is advanced,bulb 274 pushes material within compartment 286 out orifice 284.

During operation, as previously discussed with the other inventivesyringes, a hydraulic fluid is sealed between seal 336 and head 181 ofhydraulic plunger 180. As manual plunger 338 is advanced within firstchamber 332, the pressure on the hydraulic fluid is increased. In turn,the hydraulic fluid presses against hydraulic plunger 180, therebyslidably advancing hydraulic plunger 180 towards end wall 315 of outerbarrel 294. In an alternative embodiment, plunger 338 can also beconfigured to advance into second chamber 350.

Because manual plunger 338 has a substantially uniform transverse crosssectional area that is smaller than the transverse cross sectional areaof head 181, advancing manual plunger 338 under a first force at a firstspeed result in a hydraulic change or advantage which moves hydraulicplunger 180 under a second force, which is greater than the first force,and at a second speed, which is slower than the first speed. As aresult, syringe 290 is effective for dispensing highly viscous materialin a control manner using minimal exertion.

Depicted in FIG. 8 is yet another embodiment of an inventive syringe360. Syringe 360 includes barrel 292, nozzle 276, and hydraulic plunger180 as previously discussed with regard to syringe 290 in FIGS. 6 and 7.In contrast to syringe 290, however, syringe 360 has a uniquelyconfigured manual plunger 362. Manual plunger 362 has a substantiallycylindrical shaft-like configuration that extends from a first end 364to an opposing second end 366. Removably attached to first end 364 ofplunger 362 is a handle 368. Handle 368 can be removably attached in anyconventional manner such as by threaded, chemical, or frictionalengagement. Radially outwardly projecting from second end 366 of manualplunger 362 is a guide 370. Guide 370 is configured to hit againstshoulder 346 so as to prevent accidental removal of manual plunger 362from barrel 292. Guide 370 can be integrally formed with or separatelyattached to manual plunger 362.

Manual plunger 362 also includes an threaded interior surface 372bounding a channel 374 longitudinally extending through manual plunger362. Threadedly disposed within channel 374 is a plug 376. Plug 376 isconfigured to produce a liquid tight seal with manual plunger 362 so asto occlude channel 374.

During operation, a hydraulic fluid is disposed within barrel 292between seal 336 and head 181 of hydraulic plunger 180 so as to fillchannel 374 up to plug 376. As manual plunger 362 is advanced withinchambers 332 and 350, hydraulic plunger 180 is advanced under ahydraulic advantage as previously discussed with regard to FIGS. 6 and7. On occasion, however, a portion of the hydraulic fluid may leakaround seal 336, head 181, and/or plug 376. To compensate for the lossof hydraulic fluid, handle 368 is removed and a tool, such as ascrewdriver, is used to advance plug 376 within channel 374, therebyeliminating the space that was previously occupied by the lost hydraulicfluid. Alternatively, plug 376 can be removed and additional hydraulicfluid can be added.

Depicted in FIG. 9 is yet another embodiment of an inventive syringe 380incorporating features of the present invention. Syringe 380 issubstantially identical to syringe 290 discussed with regard to FIGS. 6and 7. As such, like elements will be referenced with like referencecharacters. Syringe 380 is distinguished from syringe 290 in thatsyringe 380 has a unique manual plunger 382. Manual plunger 382 has asubstantially cylindrical shaft-like configuration that extends from afirst end 384 to an opposing second end 386. Radially outwardlyprojecting from second end 386 of manual plunger 382 is a guide 388.Guide 388 is configured to hit against shoulder 346 so as to preventaccidental removal of manual plunger 382 from barrel 292. Guide 388 canbe integrally formed with or separately attached to manual plunger 382.

Manual plunger 382 also includes an interior surface 390 bounding achannel 392 longitudinally extending through manual plunger 382.Interior surface 390 includes a cylindrical first portion 394 disposedat first end 384 that bounds a first channel 396 and a cylindricalsecond portion 398 disposed at second end 388 that bounds a secondchannel 400. Second channel 400 has a diameter greater than the diameterof first channel 396 such that a shoulder 402 is formed therebetween. Anannular groove 404 is formed on first portion 394 of interior surface390. Disposed within annular groove 404 is a seal 406.

Disposed within channel 392 is a rod 408. Rod 408 is biased against seal406 so as to effect a liquid tight seal between rod 408 and manualplunger 382 at seal 406. Rod 408 has a first end 410 and an opposingsecond end 412. First end 410 of rod 408 projects past first end 384 ofmanual plunger 382 and has a handle 414 attached thereto. A pretraveldistance L extends between handle 414 and first end 384 of manualplunger 382.

Second end 412 of rod 408 is disposed within second channel 400 and hasthreads 416 formed thereon. Also disposed within second channel 400 isan adjusting collar 417. Adjusting collar 417 encircles and isthreadedly engaged to second end 412 of rod 408 so as to effect a liquidtight seal therewith. Adjusting collar 417 also has an annular exteriorsurface 418 on which a seal 420 is disposed. Seal 420 is slidabledisposed against second portion 398 of interior surface 390 so as toeffect a liquid tight seal between adjusting collar 417 and interiorsurface 390. As such, adjusting collar 417 and seal 420 produce a liquidtight seal between rod 408 and interior surface 390 of second portion398.

During operation, a hydraulic fluid is disposed within barrel 292between seal 336 and head 181 of hydraulic plunger 180 so as to fillsecond channel 400 up to seal 420. Initially, as handle 414 is advanced,only rod 408 is advanced within channel 392 of manual plunger 382. Asrod 408 advances within channel 392, the hydraulic fluid is pressurized.In turn, the pressurized hydraulic fluid begins the advancement ofhydraulic plunger 180 and thus the dispensing of material from withinnozzle 276. Once handle 414 completes its movement over the pretraveldistance L, handle 414 hits against manual plunger 382. As such, manualplunger 382 and rod 408 are advanced within chambers 332 and 350, so asto further advance hydraulic plunger 180.

Since both rod 408 and manual plunger 382 have a diameter that issmaller than the diameter of head 181 of hydraulic plunger 180, theadvancement of rod 408 and the combination of rod 408 and manual plunger382 produce a hydraulic advantage in moving hydraulic plunger 180. Thatis, application of a first force to handle 414 results in theapplication of a second greater force to hydraulic plunger 180. One ofthe benefits of advancing rod 408 independent of manual plunger 382 isthat since rod 408 has a small diameter and thus smaller transversecross sectional area than the combination of rod 408 and manual plunger382, a greater hydraulic advantage is obtained by initially using rod408. This greater hydraulic advantage is useful in overcoming the staticfriction in getting the dispensing material and hydraulic plunger 180moving. Once these items begin moving, less force is required tomaintain their movement. As such, manual plunger 382 can then be addedwhich decreases the hydraulic advantage but increases the rate at whichthe dispensing material is dispensed.

By rotating rod 408, adjusting collar 417 can be selectively positionedalong the length of second end 412 of rod 408. This movement ofadjusting collar 417 can be used to compensate for the loss of anyhydraulic fluid from barrel 292.

Depicted in FIG. 10 is yet another embodiment of an inventive syringe430 incorporating features of the present invention. Syringe 430includes a barrel 432 extending from a first end 434 to an opposingsecond end 436. Integrally molded with and radially projecting out frombarrel 432 are a pair of finger grips 438. Barrel 432 has an interiorsurface 440 bounding a chamber 442. Chamber 442 communicates with theexterior through an inlet port 444 positioned at first end 434 and anopposing outlet port 446. Outlet port 446 extends through an end wall447 positioned at second end 436.

Syringe 430 also includes a manual plunger 448. Manual plunger 448 has asubstantially cylindrical shaft-like configuration and extends from afirst end 452 to an opposing second end 454. Secured at first end 452 ofmanual plunger 448 is a handle 456. Second end 454 of manual plunger 448is slidably disposed within chamber 442. A guide 458 is secured tosecond end 454 of manual plunger 448 and is also slidably disposedwithin chamber 442. As depicted in FIG. 11, guide 458 encircles manualplunger 448 and includes a plurality of radially outwardly projectingfins 460. Each fin 460 extends either adjacent to or in direct contactwith interior surface 440 of barrel 432. Extending between each fin 460is a channel that allows fluid to pass between each of fins 460 asmanual plunger 448 is slidably moved back and forth within chamber 442.

In one embodiment, guide 458 is made of brass and is pressure-fit ontomanual plunger 448. In alternative embodiments, guide 458 can be formedfrom a variety of non-corrosive materials such as stainless steel ordifferent plastics and can be secured in any conventional manner knownto those skilled in the art. Guide 458 functions in part to minimizelateral displacement of second end 454 of manual plunger 448.Furthermore, as discussed below in greater detail, guide 458 functionsto prevent second end 454 of manual plunger 448 from accidentally beingwithdrawn from inlet port 444 of barrel 432. Encircling manual plunger448 at first end 434 of barrel 432 is a sealing assembly 464. Depictedin FIG. 12, sealing assembly 464 includes an annular seal 466 encirclingmanual plunger 448. In the embodiment depicted, seal 466 comprises aloaded lip seal with bevel lip, such as a Pip Seal. Seal 466 has anoutside wing 468 and an inside wing 470 each facing second end 436 ofbarrel 432. Outside wing 468 is biased in sealed engagement againstinterior surface 440 of barrel 432. Inside wing 470 is biased in sealedengagement against manual plunger 448. An elastic o-ring 472 is disposedbetween inside wing 470 and outside wing 468. In alternativeembodiments, seal 466 can comprise any other conventional seal orsealing material as previously discussed.

Seal 466 is retained between an annular inside washer 474 and an annularoutside washer 476. Each washer 474 and 476 encircles manual plunger 448so as to enable manual plunger 448 to slidably move therethrough. Inturn, washers 474 and 476 are retained between an inside C-clip 478 andan outside C-clip 480. Inside C-clip 478 is secured within an annulargroove 482 recessed on interior surface 440 of barrel 432. Similarly,outside C-clip 480 is secured within an annular groove 484 recessedwithin interior surface 440 of barrel 432.

During assembly, inside C-clip 478 is disposed within groove 482following which inside washer 474, seal 466, and outside washer 476 areslidably disposed within chamber 442. Finally, outside C-clip 480 is fitinto groove 484. The positioning of C-clips 478 and 480 maintains seal466 continually retained between washers 474 and 476. In one embodiment,interior surface 440 of barrel 432 radially outwardly slopes from theposition of seal 466 to inlet port 444. The outward slope typically hasan inside angle in a range between about 1° to about 100 and preferablyin a range between about 2° to about 5°. This outward sloping ofinterior surface 440 makes it easier to insert seal 466 within chamber442 without damaging seal 466.

Sealing assembly 464 not only functions to produce a liquid tight sealbetween manual plunger 448 and barrel 432, but it also interacts withguide 458 to prevent accidental removal of manual plunger 448. That is,as manual plunger 448 is drawn back, guide 458 hits against insideC-clip 478 and/or inside washer 474 to prevent further withdrawal ofmanual plunger 448.

Returning back to FIG. 10, syringe 430 also includes a hydraulic plunger490 slidably disposed within second end 436 of chamber 442. As depictedin FIG. 13, hydraulic plunger 490 includes a piston 492 having anenlarged annular head 494. A tubular shaft 496 extends from head 494 toa freely exposed terminus 498. Shaft 496 is slidably disposed withinoutlet port 446 so as to extend through end wall 447 (FIG. 10). Shaft496 has an interior surface 500 bounding a channel 502 longitudinallyextending therethrough. Channel 502 is in fluid communication with asubstantially conical, radially inwardly sloping opening 504 extendingthrough head 494. Formed on interior surface 500 of shaft 496 is athreaded portion 506. Threadedly disposed within threaded portion 506 isa plug 508. Plug 508 seals against threaded portion 506 so as to occludechannel 502. Plug 508 has a slot 510 formed in the end thereof whichenables plug 508 to be selectively advanced along or removed fromchannel 502 by used of a screw driver or other corresponding toolinserted into channel 502 from terminus 498.

Piston 492 also has an exterior surface 512 having a threaded portion514 formed thereon. A pair of opposing flats 513 are also formed onexterior surface 512 toward terminus 498. Flats 513 enable the use of awrench or other tool to hold piston 492 stationary as plug 508 isrotated into or out of channel 502. An annular restraining nut 516encircles piston 492 and is threadedly engaged with threaded portion514. Disposed between retraining nut 516 and head 494 of piston 492 is aseal 518. Seal 518 is comparable to seal 466 and can comprise a loadedlip seal, an o-ring, or any other conventional sealing structure aspreviously discussed. In the embodiment depicted, seal 518 has an insidewing 520 and an outside wing 522 each facing towards first end 535 ofbarrel 432. Disposed between wings 520 and 522 is an elastic o-ring 524.Restraining nut 516 is screwed onto piston 492 so as to retain seal 518between restraining nut 518 and head 494. As a result, inside wing 520is biased in sealed engagement against piston 492 and outside wing 522is biased and sealed engagement against interior surface 440 of barrel432.

Returning back to FIG. 10, chamber 442 is divided into a firstcompartment 526 and a second compartment 528. First compartment 526extends from sealing assembly 464 to hydraulic plunger 490. Secondcompartment 428 extends from seal 518 to end wall 447. The relativesizes of first compartment 526 and second compartment 528 depends on theposition of hydraulic plunger 490 along the length of barrel 432.Disposed within first compartment 426 is a hydraulic fluid 530 such asthat previously discussed. Accordingly, for substantially the samereasons as previously discussed with regard to the hydraulic syringes240, 290, 360, and 380, as manual plunger 448 is advanced within firstcompartment 526 under a first manual force, hydraulic plunger 490 isadvanced under an increased second force as a result of the hydraulicpressure produced by hydraulic fluid 530 within first compartment 526.

Should a portion of hydraulic fluid 530 leak from first compartment 526,plug 508 (FIG. 13) can be manually removed, as previously discussed, andadditional hydraulic fluid 530 added through channel 502. Conicalopening 504 helps to remove any air bubbles within first compartment 526prior to replacement of plug 508.

As depicted in FIGS. 10, 14, and 15, an elongated mounting arm 532,having a substantially U-shaped transverse cross section, projects fromend wall 447 to a free tip 533. Mounting arm 532 has an interior surface534 that bounds a substantially U-shaped channel 536. Channel 536 isaligned with outlet port 446. Interior surface 534 includes a retentionseat 538 disposed adjacent to tip 533, a radially enlarged groove 540disposed adjacent to end wall 447, and a transition shoulder 542disposed between retention seat 538 and enlarged groove 540.

Channel 536 is configured to receive a nozzle in the form of cartridge546. Cartridge 546 includes a barrel 548 having a annular flange 550radially outwardly projecting from one end and a curved spout 552projecting from the opposing end. Barrel 548 bounds a chamber 554configured to receive a viscous or other material for dispensing.Slidably disposed within chamber 554 is a plunger 556.

During dispensing, cartridge 546 is positioned within channel 536 suchthat flange 550 is received within groove 540 and barrel 548 is receivedwithin retention seat 538. As depicted in FIG. 15, retention seat 538 isundercut and has a configuration that is complementary to the exteriorof barrel 548. As a result, retention seat 538 of mounting arm 532snap-fits around barrel 548 of cartridge 546 so as to removably securecartridge 546 when cartridge 546 is received within channel 530. In thisconfiguration, as hydraulic plunger 490 is advanced, shaft 496 isadvanced within cartridge 546 so as to advance plunger 556 therein. Inturn, plunger 556 pushes the dispensing material out through spout 552.

Alternative embodiments of and further disclosure with regard tomounting arm 532 and cartridge 546 are disclosed in U.S. Pat. Nos.4,295,828; 4,330,280; 4,384,853; 4,4,767,326; 391,590; and 5,707,234which for purposes of disclosure are hereby specifically incorporated byreference.

Depicted in FIGS. 16-19 is a final embodiment of an inventive syringe600 incorporating features of the present invention. Syringe 600 isdescribed below in terms of structure and method of manufacture. Asdepicted in FIGS. 16 and 17, syringe 600 includes a barrel 602 extendingfrom a first end 604 to an opposing second end 606. Integrally moldedwith and radially outwardly projecting from first end 604 of barrel 602are a pair of opposing finger grips 608. Barrel 602 has an interiorsurface 610 bounding a chamber 612. Chamber 612 communicates with theexterior through an inlet port 614 positioned at first end 604 and anopposing outlet port 616. Outlet port 616 extends through an end wall618 positioned at second end 606.

As discussed below in greater detail, an annular first groove 650, anannular second groove 652, and an annular third groove 654 are recessedin spaced apart position on interior surface 610 of barrel 602 at firstend 604. Furthermore, an elongated mounting arm 532, as previouslydiscussed with regard to FIGS. 10, 14, and 15, projects from end wall618 to a free tip 533. With regard to mounting arm 532, like elementsbetween syringe 430 and syringe 600 will be referenced with likereference characters.

Slidably disposed within chamber 612 is a hydraulic plunger 660.Hydraulic plunger 660 includes a piston 662, an annular seal 664, and anut 666 securing seal 664 to piston 662. Piston 662 includes asubstantially cylindrical central body portion 668. An elongatedcylindrical shaft 670 projects from body portion 668 to a freely exposedterminus 672. Shaft 670 is slidably disposed within outlet port 616 soas to extend through end wall 618.

Piston 662 also includes a substantially cylindrical attachment post674, an annular radially outwardly projecting flange 676, and asubstantially cylindrical shoulder 678 extending therebetween. Seal 664radially encircles shoulder 678 so as to bias against flange 676. In theembodiment depicted, seal 664 comprises a loaded lip seal having aninside wing 680 and an outside wing 682 each facing towards first end604 of barrel 602. In contrast to previously discussed seal 518 whichhas a separate o-ring 524 disposed between its wings 520 and 522, seal664 has a central annular ridge 684 that is integrally formed with seal664 but performs the same function as o-ring 524. In one embodiment,seal 664 is formed from ethylene propylene (EP) but can also be madefrom a number of different materials. Furthermore, seal 664 can comprisean o-ring or any other type of conventional sealing structure such asthose previously discussed.

Nut 666 has a central aperture 691 and a plurality of peripheral holes692 each extending therethrough. Nut 666 is press fit, screwed on, orotherwise secured to post 674 so as to retain seal 664 between nut 666and flange 676. In this configuration, outside wing 680 of seal 664projects slightly past the maximum outer diameter of nut 666 and flange676.

Syringe 600 also includes a pair of retraction rods 686 each having afirst end 688 terminating at a first tip 694 and an opposing second end690 terminating at a second tip 697. Second end 690 of each retractionrod 686 is secured to nut 666. In the embodiment depicted, second end690 of each rod 686 is passed through a corresponding peripheral hole692 in nut 666. Each second tip 697 is then bent over, crimped, flaredor otherwise deformed as to prevent each second tip 697 from passingback through corresponding hole 692. An enlarge recess 696 is form onthe side of nut 666 so as to receive each second tip 697. In alternativeembodiments, rods 686 can be secured to nut 666 such as by threadedengagement, welding, adhesive, or any other convention method.

An annular guide 700 is provided having a central opening 702 extendingtherethrough and a plurality of peripheral ports 704 extendingtherethrough. Each retraction rod 686 extends through a correspondingport 704 so that guide 700 can freely slide along the length ofretraction rods 686. Each first tip 694 of retractions rods 686 is bentover or otherwise flared or enlarged so as to prevent guide 700 fromsliding off first end 688 of retraction rods 686.

During assembly, initially a spring 708 is disposed within chamber 612of barrel 602 and a plug 710 is manually clipped into channel 536 ofmounting arm 532. As discussed below in greater detail, plug 710 is usedto limit the passage of shaft 670 through outlet port 616 duringassembly of syringe 600.

Next, hydraulic plunger 660 is prepared for insertion into chamber 612.To ensure that seal 664 produces an effective liquid tight seal againstinterior surface 610 of barrel 602, outside wing 682 is configuredhaving an outer diameter that is slightly larger than the inner diameterof barrel 602. Accordingly, to minimize any potential damage to seal 664as it is passed over grooves 650, 652, and 654 of barrel 602 duringinsertion, seal 664, which is mounted to piston 662, can initially beslid within a tubular compression ring (not shown) having an innerdiameter the same as the inner diameter of barrel 602. As a result,outside wing 682 is inwardly compressed to the corresponding diameter.Seal 664 is typically retained within the compression ring for more than9 hours and preferably more than 12 hours so that outside wing 682relaxes to the diameter of the compression ring. The time to obtainrelaxation can be decreased if the seal is heated.

Due to the material properties of seal 664, outside wing 682substantially retains the relaxed formation for a time period before itbegins to outwardly expand. Accordingly, during the time period in whichoutside wing 682 is in the relaxed formation, hydraulic plunger 660 withretractions rods 686 and guide sleeve 700 are slidably advanced withinchamber 612 of barrel 602 past grooves 650, 652, and 654. To furtherassist the insertion of hydraulic plunger 660 within chamber 612, ahydraulic fluid or other form of lubricant can be applied to interiorsurface 610 of barrel 602 prior to insertion.

Seal 664 is configured such that once disposed within chamber 612,inside wing 680 biases in sealed engagement against shoulder 678 ofpiston 662 and outside wing 682 biases in sealed engagement againstinterior surface 610 of barrel 602.

Next, chamber 612 is filled to a predetermined level with a hydraulicfluid. This is accomplished by dispensing the hydraulic fluid intochamber 612 through inlet port 614. The resulting barrel assembly withhydraulic fluid is then positioned within a vacuum chamber so as tosubstantially remove all air bubbles that may be contained with thehydraulic fluid or that portion of the assembly covered by the hydraulicfluid. In one embodiment, the barrel assembly is subject to a vacuum ina range from 15 mm Hg to about 30 mm Hg with about 20 mm Hg to about 25mm Hg being more preferred. The vacuum is typically applied for a periodgreater than about 2 hours and more preferably greater than about 3hours.

As depicted in FIGS. 16 and 18, with the air removed, a c-shaped firstretaining ring 714 is disposed within first groove 650 by way of inletport 614. An annular seal 716 is next advanced within chamber 612 so asto bias against first retaining ring 714, ring 714 functioning as astop. Seal 716 has a configuration substantially identical to seal 664with an inside wing 718 and an outside wing 720 facing second end 606 ofbarrel 602. In alternative embodiments, seal 716 can have alternativeconfigurations and compositions as previously discussed. To facilitateinsertion of seal 716 over grooves 652 and 654, seal 716 can also bepositioned within a compression ring, as discussed above with regard toseal 664, prior to insertion.

A washer 722 is next positioned against seal 716 following which ac-shaped second retaining ring 724 is positioned within second groove652. Washer 722 functions as a support for seal 716 as pressure isapplied thereagainst.

Syringe 600 also includes a manual plunger 620. Manual plunger 620 has asubstantially cylindrical shaft-like configuration and extends from afirst end 622 to an opposing second end 624. Formed at first end 622 isan tapered post 626 that inwardly slopes in a frustuconicalconfiguration to a terminus 628. A plurality of annular ridges 630 areformed on post 626.

During assembly, second end 624 of manual plunger 620 is centrallypassed through washer 722 and seal 716, and then aligned with opening202 of guide 700. This assembly is disposed within a press (not shown)such that the press applies opposing forces between the bottom of plug710 and first end 622 of manual plunger 620. The force on the press isincreased until second end 624 of manual plunger 620 is press fit withinopening 202 of guide 700. The resulting assembly is then removed fromthe press. In this configuration, inside wing 718 of seal 716 is biasedin sealed engagement against manual plunger 620 and outside wing 720 isbiased in sealed engagement against interior surface 610 of barrel 602.

As depicted in FIGS. 16 and 19, a annular wiper ring 728 is positionedover first end 622 of manual plunger 620 and slidably advanced intochamber 612 so as to bias against second retention ring 724. Wiper ring728 seals against the side of manual plunger 620 to help prevent theescape of hydraulic fluid from within chamber 612 and prevent theentrance of particulate contaminate from outside of chamber 612.Examples of wiper rings include the D, SHD, and U type wiper ringsavailable from Parker Seals out of Irving, Calif. It is appreciated thatin alternative embodiments, wiper ring 728 is not required. In thisembodiment, seal 716 independently functions to prevent the escape ofhydraulic fluid and the entrance of contaminants.

An end cap 730 has an enlarged head 732 with an annular collar 734extending therefrom. A annular ridge 736 radially outwardly projectsfrom the free end of collar 734. First end 622 of manual plunger 620 isadvanced through an opening 736 extending through end cap 730. End cap730 is then press fit into inlet port 614 such that ridge 736 lockswithin third groove 654.

Finally, syringe 600 also includes a handle 632 having an enlargeannular rest 624 with a front face 636. Projecting from front face 636is a tubular stem 638 bounding an opening 640. Opening 640 is configuredsubstantially complimentary to tapered post 626. Post 626 is manuallypress fit into opening 640 such that ridges 630 engage post 638, therebyproducing a secure frictional engagement. As discussed in otherembodiments, there are of course a number of alternative ways in whichhandle 632 can be secured to manual plunger 620.

During use, manual plunger 620 is withdrawn to a fully retractedposition. Plug 710 is removed and replaced with a dispensing cartridge546 as shown and discussed with regard to FIG. 14. Depicted in FIG. 19,as manual plunger 620 is selectively advanced into chamber 612 of barrel602, guide 700 travels along retraction rods 686. The hydraulic fluidwithin chamber 612 passes either around guide 700 or through ports 704extending therethrough.

Chamber 612 is divided into a first compartment 740 and a secondcompartment 742. First compartment 740 extends from seal 716 at firstend 604 of barrel 602 to seal 664 of hydraulic plunger 660. Secondcompartment 742 extends from seal 664 to end wall 618. The sizes offirst compartment 740 and second compartment 742 vary depending on theposition of hydraulic plunger 660 along the length of barrel 602. Thehydraulic fluid, as previously discussed, is disposed within firstcompartment 740. As manual plunger 620 is advanced within firstcompartment 740, the hydraulic fluid is pressurized which in turn causeshydraulic plunger 660 to advance within barrel 602. Air within secondcompartment 742 escapes through a gap formed between shaft 670 andoutlet port 616.

Manual plunger 620 has an a transverse cross sectional area that issmaller than the transverse cross sectional area extending through seal664 of hydraulic plunger 660. Accordingly, for substantially the samereasons as previously discussed with regard to the hydraulic syringes240, 290, 360,380, and 430, as manual plunger 620 is advanced withinfirst compartment 740 under a manual first force at a first speed,hydraulic plunger 660 is advanced under a hydraulic second force greaterthan the first force and at a second speed slower than the first speed.In turn, the second force is used by shaft 670 of hydraulic plunger 660to dispense the material from cartridge 546 as previously discussed.

Once the material is dispensed from cartridge 546, manual plunger 620 ismanually retracted by pulling on handle 632. As manual plunger 620 isretracted, guide 700 slides along retraction rods 686. Once guide 700reaches first ends 688 of retraction rods 686, bent first tip portions694 hold guide 700 to rods 686. Accordingly, as manual plunger 620 isfurther retracted, retraction rods 686 and attached hydraulic plunger660 are also manually retracted within chamber 612 of barrel 602. Spring708 which is biased between end wall 618 and flange 676 of hydraulicplunger 660 also assists in the retraction of hydraulic plunger 660.

In one embodiment of the present invention, means are provided formechanically retracting hydraulic plunger 660 within chamber 612 ofbarrel 602 by retracting manual plunge 620. One example of such meanscomprises the use of retention rods 686 in conjunction with guide 700 asdiscussed above. In alternative embodiments, the means can comprise acoiled spring; a flexible line such as wire, ribbon, or cord; or anyother structure or assembly that can extend between manual plunger 620and hydraulic plunger 660. Such alternatives should be configured topermit substantially free advancement of manual plunger 620 relative tohydraulic plunger 660 while enabling manual plunger 620 to physicallyretract hydraulic plunger 660 as manual plunger 620 is retracted.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. For example, the different components and elementsof the of the various described syringes can be combined and mixed intodifferent configurations. The scope of the invention is, therefore,indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A syringe comprising: a syringe barrel having an interiorsurface bounding a chamber, the chamber extending from a first end to anopposing second end; a manual plunger coupled with the syringe barrel soas to selectively advance within the first end of the chamber; at leasta portion of a hydraulic plunger slidably disposed within the second endof the chamber, the hydraulic plunger including: a piston body; and ashaft projecting from the piston body, the shaft selectively extendingthrough an opening formed at the second end of the chamber; and a firstseal coupled with the piston body and producing a liquid tight seal withthe interior surface of the syringe barrel; a hydraulic fluid sealablydisposed within the chamber of the syringe barrel, at least a portion ofthe hydraulic fluid being disposed between the manual plunger and thehydraulic plunger such that as the manual plunger is selectivelyadvanced within the chamber, the hydraulic fluid advances the hydraulicplunger within the chamber; and means operably connected to the manualplunger for mechanically retracting the hydraulic plunger when themanual plunger is retracted.
 2. A syringe as recited in claim 1, whereinthe chamber has a substantially uniform transverse cross section alongthe length of the syringe barrel.
 3. A syringe as recited in claim 1,wherein the first seal comprises a loaded lip seal having an annularinside wing and an annular outside wing.
 4. A syringe as recited inclaim 1, wherein the means for retracting the hydraulic plungercomprises: a rod operably connected to the piston body, the rodprojecting from the piston body in a direction opposite from the shaft;and a guide secured to the manual plunger, the rod extending through aportion of the guide such that the guide can selectively advance alongat least a portion of the rod.
 5. A syringe as recited in claim 1,wherein the means for retracting comprises a rod attached to andprojecting from the hydraulic plunger toward the first end of thechamber, at least a portion of the rod being disposed within the chamberof the barrel, the manual plunger being secured to the rod such that themanual plunger can freely advance within the chamber withoutmechanically advancing the rod and the manual plunger can be retractedwithin the chamber so as to mechanically retract within the chamber therod and the hydraulic plunger attached thereto.
 6. A syringe as recitedin claim 1, further comprising a spring disposed within the second endof the chamber of the syringe barrel such that the spring can beselectively compressed between at least a portion of the hydraulicplunger and the second end of the syringe barrel.
 7. A syringe asrecited in claim 1, further comprising: the hydraulic plunger having ashaft selectively projecting through an opening formed at the second endof the syringe barrel; and a mounting arm projecting at the second endof the syringe barrel, the mounting arm having an inside surfacebounding an exposed substantially U-shaped channel extending along atleast a portion of the length thereof, the channel being configured toreceive the shaft of the hydraulic plunger.
 8. A syringe as recited inclaim 7, further comprising a cartridge having a barrel with an inletend and an opposing outlet end, the cartridge being configured to beremovably disposed within the channel of the mounting arm so as toselectively receive the shaft of the hydraulic plunger.
 9. A syringe asrecited in claim 7, further comprising a second seal secured within thechamber of the syringe barrel at the first end thereof, the second sealproducing a liquid tight seal between the interior surface of thesyringe barrel and the manual plunger.
 10. A syringe as recited in claim9, further comprising a support ring disposed against the second seal onthe side opposite the hydraulic plunger.
 11. A syringe as recited inclaim 9, further comprising a wiper ring disposed within the chamber ofthe syringe barrel, the wiper ring encircling the manual plunger.
 12. Asyringe as recited in claim 1, wherein the transverse cross sectionalarea of the manual plunger is smaller than the maximum transverse crosssectional area of the hydraulic plunger.
 13. A syringe as recited inclaim 1, wherein the hydraulic fluid has a viscosity in a range betweenabout 500 centistoke to about 5,000 centistoke.
 14. A syringecomprising: a syringe barrel having an interior surface bounding achamber, the chamber extending from a first end to an opposing secondend; a manual plunger coupled with the syringe barrel so as toselectively advance within the first end of the chamber; a hydraulicplunger slidably disposed within the second end of the chamber, thehydraulic plunger having a shaft selectively extending through anopening formed at the second end of the barrel, the hydraulic plungerincluding: a piston body; and a shaft projecting from the piston body,the shaft selectively extending through an opening formed at the secondend of the chamber; and a first seal coupled with the piston body andproducing a liquid tight seal with the interior surface of the syringebarrel; a hydraulic fluid sealably disposed within the chamber of thesyringe barrel, at least a portion of the hydraulic fluid being disposedbetween the manual plunger and the hydraulic plunger such that as themanual plunger is selectively advanced within the chamber, the hydraulicfluid advances the hydraulic plunger within the chamber; a rod extendingbetween the manual plunger and the hydraulic plunger, the rod operablyconnected to the piston body, the rod projecting from the piston body ina direction opposite from the shaft; and a guide secured to the manualplunger, the rod extending through a portion of the guide such that theguide can selectively advance along at least a portion of the rod.
 15. Asyringe as recited in claim 14, wherein the guide includes a passagewayextending therethrough, and wherein the rod includes a first end and anopposing second end, the second end of the rod being secured to thepiston body such that the rod projects toward the first end of thebarrel, the rod extending through the passageway of the guide such thatthe guide can selectively slide along the length of the rod, the firstend of the rod being configured to prevent the guide from sliding off ofthe rod.
 16. A syringe as recited in claim 14, further comprising aspring disposed within the second end of the chamber of the syringebarrel such that the spring can be selectively compressed between atleast a portion of the hydraulic plunger and the second end of thesyringe barrel.
 17. A syringe as recited in claim 14, further comprisinga mounting arm projecting at the second end of the syringe barrel, themounting arm having an inside surface bounding an exposed substantiallyU-shaped channel extending along at least a portion of the lengththereof, the channel being configured to receive the shaft of thehydraulic plunger.
 18. A syringe as recited in claim 17, furthercomprising a cartridge having a barrel with an inlet end and an opposingoutlet end, the cartridge being configured to be removably disposedwithin the channel of the mounting arm so as to selectively receive theshaft of the hydraulic plunger.
 19. A syringe as recited in claim 14,further comprising a seal secured within the chamber of the syringebarrel at the first end thereof, the seal encircling the manual plungerproducing a liquid tight seal between the interior surface of thesyringe barrel and the manual plunger.
 20. A syringe as recited in claim19, further comprising a support ring disposed against the seal on theside opposite the hydraulic plunger.
 21. A syringe as recited in claim19, further comprising a wiper ring disposed within the chamber of thesyringe barrel, the wiper ring encircling the manual plunger.
 22. Asyringe comprising: a syringe barrel having an interior surface boundinga chamber, the chamber extending from a first end to an opposing secondend; a manual plunger having a first end and an opposing second end, thesecond end of the manual plunger being slidably disposed within thefirst end of the chamber of the syringe barrel; a guide secured to andradially outwardly projecting from the second end of the manual plunger;a first seal disposed within the first end of the chamber of the syringebarrel, the first seal encircling the manual plunger so as to effect aliquid tight seal between the syringe barrel and the manual plunger; apiston including: an enlarged body slidably disposed within the secondend of the chamber of the syringe barrel; and a shaft projecting fromthe body through the second end of the syringe barrel; a second sealmounted to the piston within the second end of the chamber of thesyringe barrel, the second seal encircling the piston so as to effect aliquid tight seal between the piston and the syringe barrel; a hydraulicfluid sealed within the chamber of the syringe barrel between the firstseal and the second seal, such that as the manual plunger is selectivelyadvanced within the chamber, the hydraulic fluid advances the hydraulicplunger within the chamber; and a rod operably connected to the piston,the rod projecting toward the first end of the chamber, the rodextending through a portion of the guide such that the guide can advancerelative to the rod, and such that the manual plunger is enabled toretract the hydraulic plunger with the guide and the rod.
 23. A syringeas recited in claim 22, wherein at least one of the first seal andsecond seal comprises a loaded lip seal having an annular inside wingand an annular outside wing.
 24. A syringe as recited in claim 22, hercomprising: a mounting arm positioned at the second end of the syringebarrel, the mounting arm having an inside surface bounding an exposedsubstantially U-shaped channel extending along the length thereof, thechannel being configured to receive the shaft of the piston as thepiston is advanced within chamber of the syringe barrel; and a cartridgecomprising a barrel having an inlet end and an opposing outlet end, thecartridge being configured to be removably disposed within the channelof the mounting arm.
 25. A syringe as recited in claim 22, furthercomprising a spring disposed between at least a portion of the pistonand the second end of the barrel.
 26. A method for manufacturing ahydraulic syringe comprising: positioning at least a portion of ahydraulic plunger within a chamber of a syringe barrel, the chamberextending from a first end to an opposing second end, the hydraulicplunger being slidably positioned within the chamber such that a shaftof the hydraulic plunger selectively projects through an opening formedat the second end of the barrel; dispensing a hydraulic fluid within thechamber of the syringe barrel between the hydraulic plunger and thefirst end of the chamber; connecting a rod to the hydraulic plunger, therod projecting from the hydraulic plunger in a direction opposite of theshaft; slidably securing a guide to the rod such that the guide canslide along the length of the rod; inserting a manual plunger within thefirst end of the chamber of the syringe barrel, the manual plunger beingconfigured relative to the hydraulic plunger such that as the manualplunger is advanced within the chamber under a first force, thehydraulic plunger is advanced by the hydraulic fluid under a secondforce, the second force being greater than the first force; andconnecting the manual plunger with the guide, such that the guide andthe rod interconnect the manual plunger and the hydraulic plunger, suchthat the manual plunger is enabled to retract the hydraulic plunger withthe guide and the rod.
 27. A method as recited in claim 26, furthercomprising inserting a spring within the chamber of the syringe barrelprior to positioning of the hydraulic plunger, the spring beingselectively compressed between the hydraulic plunger and the second endof the syringe barrel.
 28. A method as recited in claim 26, wherein eachof the hydraulic plunger and the manual plunger comprises an annularseal for producing a liquid tight seal against the interior surface ofthe syringe barrel, such that the hydraulic fluid is sealed within thechamber of the syringe barrel between the annular seals.
 29. A method asrecited in claim 26, further comprising applying a relative vacuum tothe hydraulic fluid within the syringe barrel so as to substantiallyremove trapped gasses therefrom.
 30. A method as recited in claim 26,further comprising removably securing a dispensing cartridge to thesecond end of the syringe barrel, the dispensing cartridge beingconfigured to receive the shaft of the hydraulic plunger.